As illustrated in FIG. 1, an ultrasound probe 10 for a bore comprises:                a body 12 which has a cylindrical side wall 12P, with an axis A12 and a substantially constant diameter D12, that extends from a first end 12.1 to a second end 12.2,        an emission head 14 that protrudes relative to the cylindrical side wall 12P of the body 12 and is positioned in proximity to the first end 12.1, and        a connection system 16 positioned at the second end 12.2.        
Such an ultrasound probe 10 is used to inspect a bore 18 having a cylindrical side wall 18P that has an axis A18 and a diameter D18 and opens onto a face 20. The diameter D18 of the bore to be inspected is slightly greater than the diameter D12 of the ultrasound probe, in order to make it possible to introduce the body 12 provided with the emission head 14 into the bore 18 from the face 20.
During inspection, an operator introduces the ultrasound probe 10 into the bore 18 and makes it pivot inside the bore 18 so that the emission head 14 follows the circumference of the cylindrical side wall 18P of the bore 18 at a given depth P, measured from the face 20.
So that the inspection is carried out correctly, it is necessary that:
the coupling between the emission head 14 and the cylindrical side wall 18P is maintained, and
the ultrasound probe is positioned correctly in the bore during its pivoting, namely that:
the emission head 14 is positioned at the given depth P, and
the axis A12 of the body 12 of the ultrasound probe 10 is parallel to the axis A18 of the bore 18.
In practice, keeping the ultrasound probe in a correct position throughout the inspection depends on the operator's dexterity. Consequently, the reproducibility of the inspection operation is not ensured.
According to another aspect, the bore is filled with an acoustic coupling liquid in order to ensure better coupling between the emission head 14 and the cylindrical side wall 18P of the bore 18. However, the movement in translation and rotation of the ultrasound probe 10 in the bore 18 during the inspection tends to displace the acoustic coupling liquid out of the bore 18, which may lead to a loss or vitiation of the ultrasound signal. It is then necessary to add acoustic coupling liquid into the bore 18, and this has the effect of interfering with the reproducibility of the inspection operation.